In recent years control systems of various kinds have been used to control flying vehicles or other vehicles moving through a wave transmitting fluid such as radiation being transmitted through the air or sound being transmitted through water. Examples of such control devices for use in flying vehicles are shown by the U.S. Pat. No. 3,162,764 to Haviland which utilizes a number of heat sensors which are aimed at a reference body such as the sun, which is much warmer than the adjacent free space. These heat sensors, properly aimed are used to operate thrust devices to control the orientation of the vehicle.
The U.S. Pat. No. 3,571,572 to Falbel utilizes infra red heat sensors which are designed to receive radiation only from a thin strip of the earth's horizon.
The U.S. Pat. No. 2,828,930 to Herbold is somewhat similar in that it employs infra red heat detectors and uses the horizon as a reference plane.
The U.S. Pat. No. 3,472,468 to Strafford also employs thermal or infra red heat detectors to use the discontinuity in temperature between a reference body and the surrounding space, as an aid to keep the space vehicle stabilized.
The U.S. Pat. No. 3,496,367 to Eckermann utilizes a number of light sensitive elements to determine when light falling on the vehicle is within a predetermined small angle of incidence, and uses this information for controlling the attitude of the space vehicle.
The U.S. Pat. No. 3,020,407 to Merlen uses infra red sensors to produce a signal which indicates the orientation of the space vehicle.
The U.S. Pat. No. 2,740,961 to Slater relates to a stable reference apparatus using lens focussed infra red radiation detectors mounted on gimbals as part of a reference apparatus for a flying vehicle.
The U.S. Pat. No. 4,223,214 to Dorian relates to a solar tracking device designed to direct a solar energy collector toward the sun and has a mechanism for tracking the sun with some safeguards to prevent overheating.
All of the above described patents are designed for control systems in situations where cost is not a factor, and they are not practical for model or pilotless aircraft.